The food trucks typically lining downtown Minneapolis streets for the lunch crowd have mostly closed up shop now that colder weather has arrived. But city health inspectors might still be out there looking for them.

As many diners know, finding a specific food truck is a crapshoot even at the height of summer. Sometimes, inspectors have a hard time finding them, too.

As a result, about one-quarter of licensed food trucks in Minneapolis haven’t been getting an annual inspection from the city’s Health Department.

Of the 95 food trucks licensed to operate in Minneapolis two years ago, at least 29 percent were not inspected that year. Last year, there were more trucks and 25 percent went without inspection, according to a Star Tribune analysis of inspections data provided by the city.

Inspectors find and inspect most food trucks during the peak months of spring and summer by showing up at popular downtown food truck groupings, festivals and farmers markets, and then inspecting any food trucks they find.

Near the end of August, inspectors start looking for specific trucks they haven't yet inspected.

They might check social media or cruise around the city. Eventually, they might call the food truck owner. If they can't find the truck or if the truck is done operating for the year, inspectors will mark it down as "not in operation."

When inspectors tried to find trucks after September, they were largely unsuccessful. Two years ago, 81 percent of these late inspection attempts failed; last year, 51 percent failed.

Almost all of the food trucks that were ultimately not inspected in 2015 and 2016 were listed as "not in operation," although a few cases involved food trucks that either started late or went out of business in the middle of the year. Inspectors didn't record any attempted inspections for a couple of other licensed food trucks.

Taken together, these numbers seem dramatic. Aren't there regulations for this sort of thing? Here's the kicker: Minnesota health codes don't specify how often food trucks should be inspected.

"The biggest reason is the transient nature of the business," according to Steven Diaz, the manager of the Food, Pools and Lodging Services Section for the Minnesota Department of Health. He added that food trucks have been exempt from annual inspections requirements for several decades.

Diaz emphasized that food trucks should still be inspected, the state just doesn't say how often. Minneapolis aims to inspect every food truck every year, but it isn't succeeding.

"It's more of a judgment call on our part," Dan Huff, director of the city's Environmental Health division, said. "In order to protect public safety, how often do we inspect them based on our current resources and our capacity?"

Surprise health inspections by the city can happen at any time of year. For restaurants, this works just fine. As long as the inspector isn't visiting on a holiday or outside business hours, the restaurant will most likely be serving food. The short food truck season, however, complicates matters.

Minneapolis' current approach to food truck inspections should mean the trucks with the highest traffic get inspected, but there's no way to be sure if that's really happening. It's possible that other licensed trucks are operating at high volume and inspectors just aren't finding them during the peak months.

Stretched thin

Minnesota sets inspection schedules based on risk. For example, stores that only offer prepackaged food products aren't considered to be very risky — they must be inspected at least once every two years, according to Huff. Brick-and-mortar restaurants, serving fresh food prepared from raw ingredients, are riskier and must be inspected annually.

After that, priorities are set based on community impact, customer needs and the resources available to the health department, Huff said.

Staffing is one challenge. The city has 19 staffers who inspect more than 5,000 facilities, according to Huff. That number includes restaurants, hotels and pools. Some facilities even have multiple licenses to inspect, like U.S. Bank Stadium, which has about 150 licensed operations inside.

When accounting for just food inspections, the workload equals 638 inspections per person. The U.S. Food and Drug Administration (FDA) recommends one inspector for every 280 to 320 inspections.

"We're stretched pretty thin," Huff said. However, all inspector positions are filled, and the city has some extra staff working from this fall through the Super Bowl in February.

The department says the additional inspectors are needed to keep up with the rising number of establishments, of all types, that need to be inspected each year.

The growing number of food trucks is just part of that. When the city began regulating food trucks in 2010, it issued 10 licenses. This year there were 143. The jump from 2016 to 2017 was the largest annual net increase in the eight years of the program.

"Some years are stagnant, and some years we have a boom," Amy Lingo, district supervisor of business licensing for Minneapolis, said. "This year was a big one."

Outside of Minneapolis, other food trucks are either inspected by the Minnesota Department of Health or one of about 30 other local communities that, like Minneapolis, have authority to enforce state health codes. Trucks in St. Paul are inspected by the state health department because the city lost its authority in 2012 when performance reviews showed it had not been keeping up its obligations.

Diaz, of the state health department, said because the state sends inspectors to most festivals, fairs or events that have eight or more food trucks, he believes that most high-volume food trucks monitored by the state were being inspected more than once a year. The Star Tribune has not yet requested the state’s inspection data.

Staff writer Emma Nelson contributed to this report.

Data Drop is a weekly feature that uses data analysis and visualizations to explain, surprise, inform and entertain readers on topics relevant to Minnesotans. Do you have an idea you'd like us to explore? Contact MaryJo Webster

In 2011, Sean Pugh was arrested for allegedly violating terms of his release from prison. A year and a half into his roughly two-year stay in the Brown County Jail, he realized he owed the county around $17,000 — the result of a $20 daily "pay-to-stay" fee plus fees from previous jail stints.